Thompson called his father on August 31, 1999 and said he was visiting friends in St. Louis, Missouri and buying hiking supplies in preparation for a planned trip on the Pacific Crest Trail, which extends from Mexico to Washington State. He was going to start his trip in the Portland, Oregon area and hike down through California. Thompson said his father shouldn't expect to hear from him again for a couple of months. He has never been heard from again. After several months went by without contact, his father made inquiries. Searches turned up no sign of Thompson, and his father reported him missing. There's been no indication of his whereabouts since 1999 and his case remains unsolved. New York and Oregon police are investigating.